The configuration file is fine, it is the default value that's commented out.
Please check unattended-upgrades logs if it performed kernel removals: zgrep 'unused kernel' /var/log/unattended-upgrades/*.gz
Also please check if it ran at all.
The configuration file is fine, it is the default value that's commented out.
Please check unattended-upgrades logs if it performed kernel removals: unattended- upgrades/ *.gz
zgrep 'unused kernel' /var/log/
Also please check if it ran at all.